Here is the birthday girl in a recent shot outside her Carmel, Calif., home. Note her companion – the star has been a champion of furry friends for decades, and, in lieu of gifts on her big day, she asks for contributions to the Doris Day Animal Foundation.
As Day told PEOPLE in a rare 2011 interview, "I love life. I have my pets around me and good friends. I'm young at heart and I love to laugh. There's nothing better."
Born Doris Mary Ann Kappelhoff, the daughter of a Cincinnati music teacher and a homemaker, the crystal-voiced pop soprano changed her name to Day when, as a teen, she began singing on the radio. After appearances with the Big Bands of Barney Rapp and Bob Crosby, she joined Les Brown's Band and had her first hit with "Sentimental Journey."
Going solo in 1947, she successfully auditioned for Warner Bros. the following year and was cast in the studio's attempts to rival the romantic musicals that were the specialty of rival MGM.
By the mid-'50s came better roles at other studios, including her starring opposite James Stewart in Alfred Hitchcock's The Man Who Knew Too Much, the suspense thriller in which she introduced the Oscar-winning song that became her signature, "Que Sera Sera."
In 1959 she was paired for the first time with Rock Hudson, in the racy (for its time) romantic comedy Pillow Talk, which resulted in her one and only Best Actress Oscar nomination. For years after that, she was the top box office star in the world.
And, to many, she still remains No. 1 – especially at 90.
Asked what the years have taught her, the perennial charmer told PEOPLE: "Live life to the fullest … It's not coming back again."